<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh-CN" dir="ltr">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

    <script type="text/javascript">
        function showToast(toast) {
            javascript:control.showToast(toast);

        }
        function log(msg){
            console.log(msg);
        }
    </script>
    <style>
      .button {
        position: fixed;
        left: 50%;
        top: 50%;

        transform: translate(-50%, -50%);
      }
    </style>

</head>



<body>
<button class="button" onClick="showToast('Hello world')">login</button>
</body>

</html>